Zillow is a real-estate information site. In particular, it will give you an estimate of how much a house is worth, given its address. It's very impressive. Not only do they have tons of accurate information about houses, but they also have historical information, so you can see what a house sold for, and when, with a graph of its estimated value over time. It says my house is stucco when it is actually shingle, but I can only assume that this is an inaccuracy in the data from the town.
It's from the same guys that started Expedia, so they have some experience disintermediating professionals. "Disintermediating," I haven't said that in a while, how late 20th century of me!
Coolest feature: an aerial map of a neighborhood, with prices overlaid all the houses. Most annoying feature: they've overdone it with the whole "z" thing. Estimates are called "zestimates" (TM!), and the URLs end in a ".z" extension.
Typographically most annoying feature: To label themselves as being in beta, they've put the word "Beta" in their logo, and the designer tried the cute trick of using the greek letter Beta for the B. Except they've used a German double-s instead:
The German double-s is actually a lowercase letter, a ligature of a long s and a normal s. The long s in turn is the letter that everyone thinks is an f in old-fashioned texts. You know, like at the top of the Bill of Rights, where it says, "In Congrefs". So we have confusion piled on top of confusion, and Zillow seems to be in sseta (with a German accent).